(Capcom's primary storyline)
Annette Birkin was an Umbrella employee and wife of William Birkin.
Annette encountered Leon and Ada Wong in the sewers under Raccoon City. Demanding to know who they were, Ada revealed her name. A colleague of John Fay, Annette knew that she must be his girlfriend. She quickly introduced herself in return before adding in that John was dead, and that Ada would be joining him soon.
When the two entered the underground laboratory complex, Annette witnessed them take down her mutated husband. Aware of his G-Virus mutation, she nevertheless still considered him her husband. The logical reason for their actions and presence on the laboratory was simple - Ada the spy had enlisted a gullible police officer into helping her steal the G-Virus samples.
Though Leon was dismissive of the claim as a mind game of Annette's, she explained that in doing a background check on her, she realised that Ada was John Fay's girlfriend. Based on that, she concluded that Ada formed a relationship with John to gain information on Umbrella's bioweapons development program - while correct, it was not based on actual evidence. Hearing an alarm declare the self-destruct system to have been activated, Annette believed "that tramp" must have activated it. With the facility falling apart, a pipe fell from the ceiling and struck her on the head, mortally wounding Annette. When Ada tried to take the G-Virus sample Leon recovered from Annette, the injured woman shot her.
Her daughter, Sherry found her body shortly after. Annette told her that a G-Virus sample had been hidden in her pendant; she told her to escape with it, apologising for being a terrible mother and asking for her forgiveness. She died telling Sherry she still loved her.